Sodium bicarbonate use in the treatment of idiopathic intracranial hypertension.

Purpose: This retrospective case-control study from 2008 to 2022 aimed to determine the effect of adjunctive sodium bicarbonate (NaHCO₃) on treatment outcomes of and side effects of acetazolamide (ACZ) for the treatment of idiopathic intracranial hypertension (IIH).

Subjects/methods: Retrospective data was collected via chart review. 288 eyes of 144 patients with IIH, including those taking ACZ alone (control group, n = 89) vs. ACZ and NaHCO₃ (treatment group, n = 56). The primary outcome measure was time to IIH resolution. Secondary outcomes included retinal nerve fibre layer thickness (RNFL), visual field mean deviation (VFMD), visual acuity (VA), discontinuation ACZ, and patient-reported side effects of ACZ.

Results: Cox proportional hazards model for the primary outcome yielded a hazard ratio of 0.800, which was statistically insignificant (95% CI, 0.57-1.13; p = 0.200). There was no significant difference between groups when comparing RNFL, VFMD, VA, surgical intervention, or discontinuation of ACZ. The treatment group was more likely to experience side effects from ACZ prior to starting sodium bicarbonate therapy (p < 0.001). Among the treatment group, 92.7% remained on NaHCO₃ until IIH resolution, and 9 of 12 (75%) subjects reported significant improvement in ACZ-related side effects.

Conclusion: Sodium bicarbonate does not appear to impact treatment outcomes in patients taking acetazolamide for IIH. Sodium bicarbonate may represent a reasonable adjunctive medication to help mitigate acetazolamide-related side effects in this group of patients.